Progression of macular retinoschisis following intravitreal aflibercept injection for myopic macular neovascularization-a case report and review of literature.

BACKGROUND: Macular retinoschisis (MRS) and myopic macular neovascularization (mMNV) are both potentially blinding complications of high myopia. In this case report, we highlight the progression of MRS after intravitreal anti-vascular endothelial growth factor (anti-VEGF) treatment for mMNV, as well as an extensive review of the literature on this topic. CASE DESCRIPTION: A 49-year-old woman presented with two weeks of recent onset blurring and metamorphopsia in her right eye. She had high myopia in both eyes (right eye - 20/60 with - 16D, left eye - 20/20 with - 13D). Slit-lamp ophthalmoscopy found a normal anterior segment in both eyes. On fundus examination, features of pathological myopia with posterior staphyloma and peripapillary atrophy were observed in both eyes. An active mMNV, as well as intraretinal fluid, minimal perifoveal inner and outer MRS, and focal posterior vitreous traction along the inferotemporal retinal arcade, were detected on optical coherence tomography (OCT) of the right eye. The patient received an intravitreal injection of Aflibercept (2 mg/0.05 ml). RESULTS: OCT scans at two- and four-month follow-up visits revealed regressed mMNV with a taut epiretinal membrane, progressive worsening of outer MRS, and the development of multiple perifoveal retinal detachment inferior to the fovea. Pars plana vitrectomy surgery was performed for the progressive MRS with good anatomical (resolved MRS) and functional outcome (maintained visual acuity at 20/60) at the last one-month post-surgery visit. CONCLUSION: Intravitreal anti-VEGF injections for mMNV can cause vitreoretinal interface changes, exacerbating MRS and causing visual deterioration. Vitrectomy for MRS could be one of several treatment options.

Occult retinal neovascularization following intravitreal bevacizumab and laser treatment for retinopathy of prematurity.

BACKGROUND: We present a patient with retinopathy of prematurity (ROP) who developed worsening plus disease after complete regression of stage 3 ROP. The use of fundus fluorescein angiography (FFA) aided the visualization of occult neovascularization that caused the disease progression. CASE PRESENTATION: The patient was at high risk for ROP due to low birth weight of 690 g and gestational age of 25 weeks. After the diagnosis of stage 3 ROP in zone I without plus disease, she was treated initially with bilateral intravitreal bevacizumab (IVB) and followed by laser photocoagulation 5 weeks later. Despite the resolution of ROP stage, the plus disease worsened. Neither systemic risk factors nor skip laser areas were observed. Hence, FFA was performed and subsequently identified occult neovascularization with active leakage. Additional IVB and laser treatment in the capillary dropout area inside vascularized retina were added. The plus disease improved but mild arteriolar tortuosity persisted. CONCLUSIONS: Worsening of plus disease after completion of laser ablation and IVB with complete regression of stage 3 ROP is rare. Systemic risk factors such as continuous oxygen therapy and cardiovascular disease should be ruled out. FFA aided in identifying occult neovascularization and prompted further treatment.

Suppression of retinal neovascularization by intravitreal injection of cryptotanshinone.

Neovascular eye diseases, including proliferative diabetic retinopathy and retinopathy of prematurity, is a major cause of blindness. Laser ablation and intravitreal anti-VEGF injection have shown their limitations in treatment of retinal neovascularization. Identification of a new therapeutic strategies is in urgent need. Our study aims to assess the effects of Cryptotanshinone (CPT), a natural compound derived from Salvia miltiorrhiza Bunge, in retina neovascularization and explore its potential mechanism. Our study demonstrated that CPT did not cause retina tissue toxicity at the tested concentrations. Intravitreal injections of CPT reduced pathological angiogenesis and promoted physical angiogenesis in oxygen-induced retinopathy (OIR) model. CPT improve visual function in OIR mice and reduced cell apoptosis. Moreover, we also revealed that CPT diminishes the expression of inflammatory cytokines in the OIR retina. In vitro, the administration of CPT effectively inhibited endothelial cells proliferation, migration, sprouting, and tube formation induced by the stimulation of human retinal vascular endothelial cells (HRVECs) with VEGF165. Mechanistically, CPT blocking the phosphorylation of VEGFR2 and downstream targeting pathway. After all, the findings demonstrated that CPT exhibits potent anti-angiogenic and anti-inflammatory effects in OIR mice, and it has therapeutic potential for the treatment of neovascular retinal diseases.

A potent bioreducible ionizable lipid nanoparticle enables siRNA delivery for retinal neovascularization inhibition.

Small interfering RNA (siRNA) is emerging as a promising treatment for retinal neovascularization due to its specific inhibition of the expression of target genes. However, the clinical translation of siRNA drugs is hindered by the efficiency and safety of delivery vectors. Here, we describe the properties of a new bioreducible ionizable lipid nanoparticle (LNP) 2N12H, which is based on a rationally designed novel ionizable lipid called 2N12B. 2N12H exhibited degradation in response to the mimic cytoplasmic glutathione condition and ionization with a pKa value of 6.5, which remaining neutral at pH 7.4. At a nitrogen to phosphorus ratio of 5, 2N12H efficiently encapsulated and protected siRNA from degradation. Compared to the commercial vehicle Lipofectamine 2000, 2N12H demonstrated similar silencing efficiency and improved safety in the in vitro cell experiments. 2N12H/siVEGFA reduced the expression of VEGFA in retinal pigment epithelium cells and mouse retina, consequently suppressing cell migration and retinal neovascularization. In the mouse model, the therapeutic effect of 2N12H/siVEGFA was comparable to that of the clinical drug ranibizumab. Together, these results suggest the potential of this novel ionizable LNP to facilitate the development of nonviral ocular gene delivery systems.

Short Term Effect of Pre-Operative Anti-VEGF on Angiogenic and Fibrotic Profile of Fibrovascular Membranes of Proliferative Diabetic Retinopathy.

Purpose: Adjuvant, pre-operative intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections have been used to reduce peri-operative bleeding in eyes undergoing pars-plana vitrectomy for complications of proliferative diabetic retinopathy (PDR). To address the concern over their potential off-target effects of progressive fibrous contraction, we sought to dissect the transcriptional changes in the surgically extracted fibrovascular membranes (FVMs). Methods: We analyzed surgically extracted FVMs from 10 eyes: 4 eyes pretreated with intravitreal bevacizumab (IVB) and 6 untreated eyes. FVMs were digested into single cells, mRNA was extracted from endothelial cell-enriched (microbead selection with CD31) and non-endothelial cell compartments, followed by RT-qPCR quantification. We then compared the relative expression of genes involved in angiogenesis, endothelial cell integrity, and myofibroblastic processes between treated and untreated FVMs. Results: Endothelial cells from IVB pretreated FVMs showed significant reduction of VEGFA, VEGF receptors (FLT1 and KDR), and angiopoietin 2 expression as well as increased vascular endothelial cadherin and endothelin, suggesting reduced angiogenesis and enhanced vascular integrity. The non-endothelial cell fraction showed decreased expression of VEGFA and fibronectin, without significant difference in the expression of other profibrotic factors. Conclusions: Our findings confirm that adjuvant pre-operative IVB decreased fibronectin and increase endothelin-1 expression without affecting other profibrotic gene expression, uncovering an important interaction between IVB and endothelin-1 that deserves further study.

Can objective parameters in optical coherence tomography be useful markers in the treatment and follow-up of type 1 and type 2 macular neovascularizations related to neovascular age-related macular degeneration?

PURPOSE: The aim of this study was to compare the responses of type 1 and type 2 macular neovascularizations (MNV) caused by neovascular type age-related macular degeneration (n-AMD) to intravitreal anti-vascular endothelial growth factor (VEGF) treatments using quantitative parameters determined by optical coherence tomography (OCT). Additionally, it was also intended to assess the connections between these quantitative parameters and changes in best-corrected visual acuity (BCVA) and the number of intravitreal anti-VEGF injections required within a year. MATERIALS AND METHODS: In our retrospective and observational study, the data of 90 eyes of 90 patients diagnosed with n-AMD and treated with intravitreal anti-VEGF with the "Pro re nata" method were evaluated. Subtypes of existing MNVs were distinguished with previously taken optical coherence tomography angiography (OCTA) images. In spectral domain OCT examinations, central macular thickness (CMT) and central macular volume (CMV) values were recorded at baseline and 12th month. The number of intravitreal anti-VEGF injections during the 12 month follow-up period was also recorded for each patient. Obtained data were compared between MNV types. RESULTS: Of the n-AMD cases examined in the study, 56.66% had type 1 MNV and 43.34% had type 2 MNV. The mean baseline BCVA logMAR values in eyes with type 2 MNV (1.15 ± 0.43) were higher than those observed in eyes with type 1 MNV (0.76 ± 0.42) (p = 0.001). Similarly, mean baseline CMT and CMV values in eyes with type 2 MNV were higher than those observed in eyes with type 1 MNV (respectively 424.89 ± 49.46 µm vs. 341.39 ± 37.06 µm; 9.17 ± 0.89 µm3 vs. 8.49 ± 0.53 µm3; p < 0.05). After 12 months of treatment, logMAR values of BCVA (0.86 ± 0.42) in subjects with type 2 MNV were higher than those in subjects with type 1 MNV (0.57 ± 0.37) (p = 0.001). Mean CMT and CMV values at 12th month in subjects with type 2 MNV (379.11 ± 46.36 µm and 8.66 ± 0.79 µm3, respectively) were observed to be higher than those with type 1 MNV (296.95 ± 33.96 µm and 8.01 ± 0.52 mm3, respectively) (p < 0.05). In type 2 MNVs, positive correlations were observed between both baseline and 12th month BCVA logMAR values and baseline CMV (p < 0.05). Similarly, in type 2 MNVs, a positive correlation was observed between 12th month BCVA logMAR values and 12th month CMV (p < 0.05). The total number of intravitreal anti-VEGF injections at 12 months was similar in both groups (p = 0.851). CONCLUSION: In this study, in which we performed a subtype analysis of MNV cases, we observed that the visual function was worse at the beginning and the end of the 12th month, and the CMT and CMV values were higher in the type 2 MNV group compared to the type 1 MNV cases. In addition, we found significant correlations between BCVA logMAR values and CMV values in type 2 MNV cases. In the follow-up of these cases, CMT, which is a more widely used quantitative method, and CMV, which is a newer OCT measurement parameter, may be more useful in patient follow-up and evaluation of treatment efficacy, especially for type 2 MNV cases.

Assistance Burden Comparison Between Age-Related Macular Degeneration and Retinal Angiomatous Proliferation Over a Three-Year Follow-up.

BACKGROUND AND OBJECTIVE: We compared assistance burden between neovascular age-related macular degeneration (nAMD) and retinal angiomatous proliferation (RAP) under intravitreal anti-vascular endothelial growth factor (anti-VEGF) treatment on a treat-and-extend (T&E) regimen in a third-level hospital in a developed country. PATIENTS AND METHODS: This retrospective study using data from the Fight Retinal Blindness! Registry included patients treated between January 2016 and December 2020. Final event was established as best corrected visual acuity (BCVA) lower than 20 Early Treatment Diabetic Retinopathy Study letters. According to choroidal neovascularization (CNV), three different study groups were established: type 1, 2, and 3. RESULTS: A total of 285 eyes of 227 patients were included. Mean age was 80.1 ± 6.5, 79.1 ± 7.9, and 81.2 ± 7.2 years, for the three study groups, respectively. Mean injections were 16.0 ± 4.8, 16.5 ± 4.1, and 14.1 ± 5.7, respectively; and mean number of visits were 17.9 ± 4.3, 18.2 ± 3.1, and 16.8 ± 5.3, respectively. No differences were found (P > 0.05). Survival curves and log-rank analysis also showed no differences (P = 0.344). Cox proportional hazard models showed that a lower baseline BCVA, subfoveal geographic atrophy (GA), and subfoveal fibrosis (SF) were associated with a higher risk of reaching ≤ 20 letters. CONCLUSIONS: nAMD and RAP under a T&E regimen indicate a high assistance burden during the first three years. The presence of subfoveal GA or SF are associated with a BCVA lower than 20 letters. [Ophthalmic Surg Lasers Imaging Retina 2024;55:197-203.].

Longitudinal Characteristics of Choroidal Neovascular Membrane in Pediatric Patients.

PURPOSE: To report the clinical and imaging characteristics, including optical coherence tomography angiography (OCTA), and treatment outcomes of choroidal neovascular membranes (CNVMs) in children. DESIGN: Retrospective clinical cohort study. METHODS: Thirty eyes from 25 children (56% girls) with CNVM from 2 centers were examined from 2005 to 2022. Clinical features, imaging findings, treatment regimens, and outcomes are described. RESULTS: The most common causes of CNVM were idiopathic (48%) and inflammatory (20%). At diagnosis, most CNVMs were unilateral (80%), active (83.3%), and juxtafoveal (46.7%). Twenty-five eyes (83.3%) of 21 patients (84%) were treated. The most common first-line treatment was intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) (92%), with a retreatment rate of 52.2% at an average of 237 days. The average number of total injections per eye was 2.3. Injections were safely administered in the clinic (52.2%). A gain of 3 lines or 15 ETDRS (Early Treatment Diabetic Retinopathy Study) letters was observed at final visit. The average duration of follow-up was 56.46 ± 42.51 months. No ocular or systemic complication related to treatment was reported. Sixteen eyes (64%) had OCTA images at both presentation and final visit, which showed a decrease in CNVM vessel density and vessel-length density, and in the height of retinal pigment epithelium detachment (RPED). CONCLUSIONS: There are a variety of underlying etiologies for pediatric CNVMs, which are most often unilateral. Treatment with intravitreal anti-VEGF can be beneficial and does not often require frequent or chronic dosing. OCTA demonstrated a decrease in the CNVM vessel density and vessel-length density as well as in the height of RPED.

The Anti-Diabetic Drug Metformin Suppresses Pathological Retinal Angiogenesis via Blocking the mTORC1 Signaling Pathway in Mice (Metformin Suppresses Pathological Angiogenesis).

PURPOSE: Metformin, a biguanide antihyperglycemic drug, can exert various beneficial effects in addition to its glucose-lowering effect. The effects of metformin are mainly mediated by AMP-activated protein kinase (AMPK)-dependent pathway. AMPK activation interferes with the action of the mammalian target of rapamycin complex 1 (mTORC1), and blockade of mTORC1 pathway suppresses pathological retinal angiogenesis. Therefore, in this study, we examined the effects of metformin on pathological angiogenesis and mTORC1 activity in the retinas of mice with oxygen-induced retinopathy (OIR). METHODS: OIR was induced by exposing the mice to 80% oxygen from postnatal day (P) 7 to P10. The OIR mice were treated with metformin, rapamycin (an inhibitor of mTORC1), or the vehicle from P10 to P12 or P14. The formation of neovascular tufts, revascularization in the central avascular areas, expression of vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) 2, and phosphorylated ribosomal protein S6 (pS6), a downstream indicator of mTORC1 activity, were evaluated at P10, P13, or P15. RESULTS: Neovascular tufts and vascular growth in the central avascular areas were observed in the retinas of P15 OIR mice. The formation of neovascular tufts, but not the revascularization in the central avascular areas, was attenuated by metformin administration from P10 to P14. Metformin had no significant inhibitory effect on the expression of VEGF and VEGFR2, but it reduced the pS6 immunoreactivity in vascular cells at the sites of angiogenesis. Rapamycin completely blocked the phosphorylation of ribosomal protein S6 and markedly reduced the formation of neovascular tufts. CONCLUSIONS: These results suggest that metformin partially suppresses the formation of neovascular tufts on the retinal surface by blocking the mTORC1 signaling pathway. Metformin may exert beneficial effects against the progression of ocular diseases in which abnormal angiogenesis is associated with the pathogenesis.

Extending Peripheral Retinal Vascularization in Retinopathy of Prematurity Through Regulation of VEGF Signaling.

PURPOSE: Experimental studies provide evidence that regulation of VEGF receptor-2 signaling in endothelial cells orders cell divisions and extends developmental angiogenesis while inhibiting pathologic intravitreal angiogenesis and has relevance to retinopathy of prematurity (ROP). We tested the hypothesis that intravitreal anti-VEGF would extend vascularization into peripheral avascular retina in human type 1 ROP compared with controls. DESIGN: Retrospective, nonrandomized treatment comparison. METHODS: The study was conducted at an academic institution, with the study population comprising all premature infants screened for ROP from January 2019 through December 2022. The experimental group included type 1 ROP treated with bilateral bevacizumab (0.25 mg) and had adequate fundus imaging by a certified ophthalmic photographer at 2 examinations: within 2 weeks of treatment and 1-3 weeks later. A control group included gestational age- and birthweight-matched infants with ROP less severe than type 1 ROP. The main outcome measure was extent of temporal retinal vasculature measured by a masked analyst between treated and control eyes. Paired and nonpaired t tests were used. RESULTS: Of 382 screened infants, 34 developed type 1 ROP; 11 comprised the experimental group and 11 the control group. At baseline, there was a trend toward shorter temporal vascular extent in treatment compared with control groups (3667±547 vs 4262±937 pixels, 95% CI -1277, 88; P = .084) but no difference between groups at follow-up (P = .945). Vascular extension was significantly greater in the treatment than control (872±521 vs 253±151 pixels, 95% CI 262, 977; P = .003), showing catch-up growth. CONCLUSIONS: This clinical evidence supports laboratory-based studies that regulation of VEGF using an intravitreal anti-VEGF agent increases developmental angiogenesis into the peripheral avascular retina while inhibiting pathologic intravitreal angiogenesis in ROP.

Evaluation of retinal vascularization in retinopathy of prematurity regressed after intravitreal ranibizumab monotherapy or without treatment based on fluorescein angiography.

To investigate the fluorescein angiography (FA) findings and compare the extent of retinal vascularization in retinopathy of prematurity (ROP), recovered after intravitreal ranibizumab (IVR) monotherapy and those regressed spontaneously. Infants with a history of ROP who underwent FA between April 2018 and November 2021 were retrospectively included. The patients were divided into two groups based on whether they had received IVR (IVR group) or had ROP that regressed spontaneously without treatment (untreated group). The differences between the two groups in zone II ROP were also compared, to equalize the subgroups as much as possible in terms of disease severity. FA findings were recorded. The extent of vascularization was measured by the ratio of the distance from the center of the disk to the border of the vascularized zone (DB) and the distance from the center of the disk to the center of the fovea (DF). The width of the persistent avascular retina (PAR) was counted by disc diameters (DD). One hundred and ten eyes of 55 infants were included in the IVR group and 76 eyes of 38 babies in the untreated group. The ratio of abnormal shape of vessels was significantly higher in the IVR group than in the untreated group (50.9% vs. 35.5%; P = 0.038), while the linear choroidal filling pattern, tortuosity of vessels over the posterior pole, dye leakage, anomalous branching of vessels, circumferential vessels, arteriovenous shunt, abnormal capillary bed, and macular abnormalities were similarly. There was a smaller temporal DB/DF ratio (4.48 vs. 4.63; P = 0.003) and greater PAR (2.63 vs. 1.76; P < 0.001) in the IVR group compared to the untreated group. In zone II ROP, the progression of retinal vascularization was significantly larger in the IVR group than that in the untreated group (P = 0.003), while no statistical differences were observed in FA features, the DB/DF ratio, and PAR between the two subgroups. The residual vascular abnormalities and PAR may be common results of ROP regression. The DB/DF ratio of 4.0 temporally and 3.3 nasally could be used as the preliminary indicators for safe retinal vascularization in the completion of ROP regression.

Protective effect of ethyl ferulate against hypoxic injury in retinal cells and retinal neovascularization in an oxygen-induced retinopathy model.

BACKGROUND: Pathological neovascularization is a major cause of visual impairment in hypoxia-induced retinopathy. Ethyl ferulate (EF), the natural ester derivative of ferulic acid commonly found in Ferula and Angelica Sinensis, has been shown to exert antioxidant, neuroprotective, and anti-inflammatory properties. However, whether EF exerts a protective effect on retinal neovascularization and the underlying mechanisms are not well known. PURPOSE: The aim of the study was to investigate the effect of EF on retinal neovascularization and explore its underlying molecular mechanisms. STUDY-DESIGN/METHODS: We constructed hypoxia models induced by cobalt chloride (CoCl2) in ARPE-19 cells and Rhesus choroid-retinal vascular endothelial (RF/6A) cells in vitro, as well as a retinal neovascularization model in oxygen-induced retinopathy (OIR) mice in vivo. RESULTS: In this work, we demonstrated that EF treatment inhibited hypoxia-induced vascular endothelial growth factor A (VEGFA) expression in ARPE-19 cells and abrogated hypoxia-induced tube formation in RF/6A cells. As expected, intravitreal injection of EF significantly suppressed retinal neovascularization in a dose-dependent manner in OIR retinas. We also found that hypoxia increased VEGFA expression by blocking autophagic flux, whereas EF treatment enhanced autophagic flux, thereby reducing VEGFA expression. Furthermore, EF activated the sequestosome 1 (p62) / nuclear factor E2-related factor 2 (Nrf-2) pathway via upregulating oxidative stress-induced growth inhibitor 1 (OSGIN1) expression, thus alleviating oxidative stress and reducing VEGFA expression. CONCLUSION: As a result of our findings, EF has an inhibitory effect on retinal neovascularization, implying a potential therapeutic strategy for hypoxia-induced retinopathy.

Retinal Angiomatous Proliferation in a Patient with Retinitis Pigmentosa.

Retinal angiomatous proliferation (RAP) and other types of choroidal neovascularization (CNV) are very rarely reported in patients with retinitis pigmentosa (RP). We present a case report of a 91-year-old patient with an obvious RP phenotype, who presented with a sudden onset of vision worsening and metamorphopsia in the left eye. Genetic testing on the UK inherited retinal disease panel did not identify a pathogenic variant. Multimodal imaging comprising optical coherence tomography (OCT), OCT angiography, and fluorescein and indocyanine green angiography showed a RAP lesion in the left macula. The patient received three treatments of monthly injections of aflibercept, with excellent morphological and functional outcomes. Taking into account the patient's age at presentation of the RAP lesion, it is not clear whether the RAP was associated or coincidental with RP. This case report highlights the importance of possessing an awareness that RAP lesions can occur in RP. Moreover, due to a good response and potential safety concerns with continuous anti-VEGF injections in RP patients, a pro re nata (PRN) regimen might be the safest option.

Quantitative Evaluation of Progression of Retinal Vascularization After 60 Weeks Postmenstrual Age in Infants Treated With Bevacizumab.

BACKGROUND AND OBJECTIVE: To investigate the progression of retinal vascularization after 60 weeks postmenstrual age (PMA) in eyes treated with intravitreal bevacizumab (IVB). PATIENTS AND METHODS: Twenty-seven eyes that were treated with IVB and underwent two consecutive fluorescein angiographies (FA) after 60 weeks PMA. Horizontal disc diameter (DD), disc-to-fovea (DF) distance, and length of temporal retinal vascularization (LTRV) were measured in pixels on the two consecutive angiograms. RESULTS: Mean age at first and final FA sessions were 77.7 ± 15.7 and 168.0 ± 49.0 weeks PMA, respectively. The DF/DD ratio was 3.30 ± 0.46 and 3.16 ± 0.46 in the first and final FAs (P = 0.001), respectively. The LTRV/DD ratio was 13.38 ± 2.12 and 13.15 ± 2.13 in the first and final FAs (P = 0.027), respectively. The LTRV/DF ratio was 4.06 ± 0.39 and 4.17 ± 0.42, respectively (P = 0.032). CONCLUSION: Temporal retinal vascularization did not progress despite an average follow-up of 90 weeks in pixel units and DD. [Ophthalmic Surg Lasers Imaging Retina 2023;54:417-424.].

Xanthine derivative KMUP-1 ameliorates retinopathy.

Retinal neovascularization (RNV) and cell apoptosis observed in retinopathy are the most common cause of vision loss worldwide. Increasing vascular endothelial growth factor (VEGF), which was driven by hypoxia or inflammation, would result in RNV. This study investigated the anti-inflammatory and anti-apoptotic xanthine-based derivative KMUP-1 on hypoxia-induced conditions in vitro and in vivo. In the oxygen-induced retinopathy animal model, KMUP-1 mitigated vaso-obliteration and neovascularization. In the cell model of hypoxic endothelium cultured at 1% O2, KMUP-1 inhibited endothelial migration and tube formation and had no cytotoxic effect on cell growth. Upregulation of pro-angiogenic factors, HIF-1α and VEGF, and pro-inflammatory cytokines, IL-1ß and TNF-α, expression in the retinal-derived endothelial cells, RF/6 A cells, upon hypoxia stimulation, was suppressed by KMUP-1 treatment. RF/6 A cells treated with KMUP-1 showed a reduction of PI3K/Akt, ERK, and RhoA/ROCKs signaling pathways and induction of protective pathways such as eNOS and soluble guanylyl cyclase at 1% O2. Furthermore, KMUP-1 decreased the expression of VEGF, ICAM-1, TNF-α, and IL-1ß and increased the BCL-2/BAX ratio in the oxygen-induced retinopathy mouse retina samples. In conclusion, the results of this study suggest that KMUP-1 has potential therapeutic value in retinopathy due to its triple effects on anti-angiogenesis, anti-inflammation, and anti-apoptosis in hypoxic endothelium.

Efficiency co-delivery of ellagic acid and oxygen by a non-invasive liposome for ameliorating diabetic retinopathy.

Diabetic retinopathy (DR) is one of the serious complications of diabetes, which has become the fourth leading cause of vision loss worldwide. Current treatment of DR relies on intravitreal injections of antiangiogenic agents, which has made considerable achievements in reducing visual impairment. However, long-term invasive injections require advanced technology and can lead to poor patient compliance as well as the incidence of ocular complications including bleeding, endophthalmitis, retinal detachment and others. Hence, we developed non-invasive liposomes (EA-Hb/TAT&isoDGR-Lipo) for efficiency co-delivery of ellagic acid and oxygen, which can be administered intravenously or by eye drops. Among that, ellagic acid (EA), as an aldose reductase inhibitor, could remove excessive reactive oxygen species (ROS) induced by high glucose for preventing retinal cell apoptosis, as well as reduce retinal angiogenesis through the blockage of VEGFR2 signaling pathway; carried oxygen could ameliorate DR hypoxia, and further enhanced the anti-neovascularization efficacy. Our results showed that EA-Hb/TAT&isoDGR-Lipo not only effectively protected retinal cells from high glucose-induced damage, but also inhibited VEGF-induced vascular endothelial cells migration, invasion, and tube formation in vitro. In addition, in a hypoxic cell model, EA-Hb/TAT&isoDGR-Lipo could reverse retinal cell hypoxia, thereby reducing the expression of VEGF. Significantly, after being administered as an injection or eye drops, EA-Hb/TAT&isoDGR-Lipo obviously ameliorated the structure (central retinal thickness and retinal vascular network) of retina by eliminating ROS and down-regulating the expression of GFAP, HIF-1α, VEGF and p-VEGFR2 in a DR mouse model. In summary, EA-Hb/TAT&isoDGR-Lipo holds great potentials in improvement of DR, which provides a novel approach for the treatment of DR.

The Antiangiogenic Effect and Ocular Pharmacology of Novel Modified Nonsteroidal Anti-Inflammatory Drugs in the Treatment of Oxygen-Induced Retinopathy.

Purpose: To evaluate the hypothesis that 3 novel compounds, OXT-328, Q-922, and CL-717 show efficacy in the treatment of oxygen-induced retinopathy (OIR) and whether or not their route of administration is intravitreal, topical, or systemic. Methods: The OIR mouse model, characterized by an avascular area (AVA) and a neovascular area (NVA) of the retina, was used to study retinopathy of prematurity and other retinal diseases characterized by abnormal vessel growth. We measured the effect of our compounds on both the AVA and NVA in whole mounts of mouse retinal tissue. We also evaluated their ability to prevent new vessel formation in chicken chorioallantoic membranes (CAMs). Finally, we measured the in vitro uptake and biodistribution of topically applied CL-717 in human eye explants. Results: In mice with OIR, compared to controls, a single intravitreal administration of Q-922 or OXT-328 significantly reduced both AVA and NVA. CL-717 administered as eye drops over 5 days also reduced AVA and NVA, whereas OXT-328 eye drops had no effect. Q-922 given intraperitoneal (150 mg/kg/day × 5 days) reduced AVA and NVA. Remarkably, explanted human eyes bathed in CL-717 show rapid uptake and biodistribution in ocular tissues. In the chicken CAM model, all 3 compounds reduced the formation of new blood vessels by about one-third. No side effect in mice was observed, except for mild ocular surface irritation with Q-922. Conclusions: Systemic administration of Q-922 or topical administration of CL-717 holds particular promise for a simplified treatment of proliferative retinopathies without the necessity of intravitreal injections.

Therapeutic effect of ultra-long-lasting human C-peptide delivery against hyperglycemia-induced neovascularization in diabetic retinopathy.

Rationale: Neovascularization is a hallmark of the late stages of diabetic retinopathy (DR) leading to blindness. The current anti-DR drugs have clinical disadvantages including short circulation half-lives and the need for frequent intraocular administration. New therapies with long-lasting drug release and minimal side effects are therefore needed. We explored a novel function and mechanism of a proinsulin C-peptide molecule with ultra-long-lasting delivery characteristics for the prevention of retinal neovascularization in proliferative diabetic retinopathy (PDR). Methods: We developed a strategy for ultra-long intraocular delivery of human C-peptide using an intravitreal depot of K9-C-peptide, a human C-peptide conjugated to a thermosensitive biopolymer, and investigated its inhibitory effect on hyperglycemia-induced retinal neovascularization using human retinal endothelial cells (HRECs) and PDR mice. Results: In HRECs, high glucose conditions induced oxidative stress and microvascular permeability, and K9-C-peptide suppressed those effects similarly to unconjugated human C-peptide. A single intravitreal injection of K9-C-peptide in mice resulted in the slow release of human C-peptide that maintained physiological levels of C-peptide in the intraocular space for at least 56 days without inducing retinal cytotoxicity. In PDR mice, intraocular K9-C-peptide attenuated diabetic retinal neovascularization by normalizing hyperglycemia-induced oxidative stress, vascular leakage, and inflammation and restoring blood-retinal barrier function and the balance between pro- and anti-angiogenic factors. Conclusions: K9-C-peptide provides ultra-long-lasting intraocular delivery of human C-peptide as an anti-angiogenic agent to attenuate retinal neovascularization in PDR.

QUANTIFIED ANASTOMOTIC AREAS OF NEOVASCULARIZATION AS FACTORS ASSOCIATED WITH FREQUENT RECURRENCE IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To investigate the quantitative characteristics of anastomoses of macular neovascularization (MNV) in neovascular age-related macular degeneration using optical coherence tomography angiography according to the frequency of intravitreal injections. METHODS: Eighty-six eyes of 86 patients treated for neovascular age-related macular degeneration were classified into two groups based on the number of intravitreal injections administered over 12 months: stable (<3) and unstable (≥3). Anastomotic areas were defined as areas surrounded by neighboring vessels in the MNV; their total number, mean area, maximal and minimal diameters (i.e., maximal and minimum Feret diameters), and ratio (Feret aspect ratio) were analyzed in the inner and outer areas of the MNV. RESULTS: Forty-four and 42 eyes were classified into the stable and unstable groups, respectively. The eyes in the unstable group had larger anastomotic areas with longer minimum Feret diameters and longer perimeters in the outer MNV. In the logistic regression analysis, instability was associated with a larger anastomotic area and a longer minimum Feret diameter in the outer MNV. Multivariate analysis revealed that a longer minimum Feret diameter in the outer MNV was the most significant factor ( P = 0.03). CONCLUSION: The quantitative characteristics of the anastomotic areas in the MNV might indicate the need for intravitreal injections in patients with neovascular age-related macular degeneration.

Biomimetic, Injectable, and Self-Healing Hydrogels with Sustained Release of Ranibizumab to Treat Retinal Neovascularization.

Retinal neovascularization (RNV) is a typical feature of ischemic retinal diseases that can lead to traction retinal detachment and even blindness in patients, in which the vascular endothelial cell growth factor (VEGF) plays a pivotal role. However, most anti-VEGF drugs currently used for treating RNV, such as ranibizumab, need frequent and repeated intravitreal injections due to their short intravitreal half-life, which increases the incidence of complications. Herein, a hydrogel intravitreal drug delivery system (DDS) is prepared by a dynamic Schiff base reaction between aminated hyaluronic acid and aldehyde-functionalized Pluronic 127 for sustained release of ranibizumab. The prepared hydrogel system named HP@Ran exhibits excellent injectability, self-healing ability, structural stability, cytocompatibility, and blood compatibility. According to an in vitro drug release study, the hydrogel system continuously releases the model drug bovine serum albumin for more than 56 days. Importantly, in an in vivo rabbit persistent RNV model, the HP@Ran hydrogel system continuously releases pharmacologically active ranibizumab for more than 7 weeks and also exhibits superior anti-angiogenic efficacy over ranibizumab treatment by decreasing vascular leakage and neovascularization at 12 weeks. Thus, the developed HP@Ran hydrogel system possesses great potential for intravitreal DDS for the treatment of RNV.